public class Likou_erchashujiedian {
    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     *     int val;
     *     TreeNode left;
     *     TreeNode right;
     *     TreeNode() {}
     *     TreeNode(int val) { this.val = val; }
     *     TreeNode(int val, TreeNode left, TreeNode right) {
     *         this.val = val;
     *         this.left = left;
     *         this.right = right;
     *     }
     * }
     */
//    class Solution {
//        int usesize = 0;
//        public int countNodes(TreeNode root) {
//            if(root==null){
//                return 0;
//            }
//            usesize++;
//            countNodes(root.left);
//            countNodes(root.right);
//            return usesize;
//        }
//    }
}
